Turbo-machines such as compressors and turbines generally include a rotating assembly having a centrally located rotor shaft and a plurality of rows of rotating blades attached thereto, and a corresponding plurality of rows of stationary vanes connected to the casing of the turbo-machine and interposed between the rows of rotating blades. A working fluid such as air or combustion gas flows through the rows of rotating blades and stationary vanes to transfer energy between the working fluid and the turbo-machine.
A rotating blade of a turbo-machine typically includes a root section attached to the rotor, a platform section connected to the root section, and an airfoil section connected to the platform section on a side opposite from the root section. The edges of platform sections of adjacent blades in a row of blades abut each other to form a portion of the boundary defining the flow path for the working fluid. While it would be desirable to have adjacent platforms abut in a perfect sealing relationship, the necessity to accommodate thermal growth and machining tolerances results in a small gap being maintained between adjacent platforms.
Prior art turbo-machines have incorporated many types of devices to seal the gap between the platforms of adjacent blades, and also to provide a mechanical damping therebetween. For low temperature applications such as a compressor, U.S. Pat. Nos. 4,422,827 and 4,580,946 teach the use of an elastomeric material to seal the gap between adjacent blade platforms. For high temperature applications such as a combustion turbine, U.S. Pat. Nos. 4,326,835 and 5,281,097 teach the use of a metal plate affixed under the platforms of adjacent blades to seal the gap. Furthermore, it is known to provide sealing and damping functions in one device installed under the blade platforms, such as is shown in U.S. Pat. Nos. 3,751,183; 4,872,812; 5,785,499; and 5,803,710. Each of the above cited patents is incorporated by reference herein. The prior art devices are either expensive to manufacture, complicated to install, or lack sufficient sealing effectiveness for modern combustion turbine applications.
Accordingly, it is an object of this invention to provide an improved device for sealing and damping between the platforms of adjacent rotating blades in a turbo-machine. It is a further object to provide a device for sealing and damping that can be manufactured by simple, known manufacturing techniques, that is easy to install and to remove, and that provides improved sealing effectiveness.